Electric valve translating circuits



Aug. 10, 1943. A M TT 2,326,550

ELECTRIC VALVE TRANSLATING CIRCU I'IS Filed 001;; l, 1941 Fig.1. 4

ll I Inventor: Albert H. Mitt-a2,

- Patented Aug. 10, 1943 ELECTRIC VALVE TRANSLATING CIRCUITS Albert aiming, Schenectady, N. v., assig'nor to General Electric company, a corporation of New York Application October 1, 1941, Serial No. 413,231

' Claims. (01.175-363) My invention relates to electric valve translat ing circuits and more particularly to electric circuits having electric valve means of the type employing an ionizable medium.

in parallel. Theme of the current dividing reactor serves to increase the voltage which is ap plied to one 01' the electric valves if that electric valve fails to become conductive at the desired In electric translating circuits which employ 5 instant. In this way, the electric valve in each electric valves of the controlled type, such as pair which tends to lag the other valve is conthose having control members which determine trolled by impressing on its control member an the time of initiation of conduction of current increased voltage. Y through the electric valve means to control an Another aspect-of my invention relates to an electrical condition or an associated circuit, it is improved arrangement including electric valves of importance to provide control circuits which which are provided with relieving anodes which not only control the electrical condition precisely effect the transmissionoi the excitationcurrent in response to a controlling influence, but which to the relieving anodes as soon as an are disare of a simple and rugged construction and charge is established within the electric valve which do not require frequent repair or replacee means due to the proper energization oi. the asment in order to assure continuity of service. sociated immersion-ignitor control member. In In accordance with the teachings of my invenone of the modifications, a second current dividtion described hereinafter, Iprovide new and iming reactor isemployed to relieve the duty improved control or excitation circuits for electric posed on the unidirectional conducting device valve translating apparatus which afford advanwhich is connected between the excitation means tages not obtainable by the use of prior art aror circuit and the control members. In this manrangements. ner, the life of the excitation system is substan- It is an object of my invention to provide new tially'increased due to the reduction of the duty and improved electric valve translating apparaimposed on the unidirectional conducting detus. vices.

It is another object of my invention to provide For a better understanding of my invention, new and improved control or excitation circuits reference may be had to the following descrlpfor electric valve translating apparatus. tion taken in connection with theaocompanying It is a further object of my invention to prodrawing, and its scope will be pointed out in the vide new and improved excitation circuits for appended. claims. Figs. 1, 2, 2a and 3 diagramelectric valve apparatus which are intended to v matically illustrate embodiments oimyinvention operate in parallel relationship during predeteras applied to polyphase electric valve rectifying mined intervals of time. equipment.

It is a still further object of my invention to Referring now to Fig. 1 of the accompanying provide new and improved control and ex'cfta- '35 drawing, my invention is there illustrated as aption circuits for electric valve means of the type plied to an electric valve translating system, each which employ an ionizable medium, such as a as a rectiiyingsystem, for transmitting power gas or a vapor, and which include immersion.- irom a polyphase alternating current supply cirignitor type control members. -cuit l to a direct'current' load circuit including Briefly stated, in the illustrated embodiments 40 a positive conductor 2 and a negative conductor in my'invention I provide new and improved 3. The translating system including an electri- A excitation circuits for electric valves comprising cal network having a plurality oi electrically dis- I immersion-ignitor type control members and placed phase windings, at least two of which are which are intended to operate in parallel reladisplaced or arranged to conduct current during tionship during accurately determinable interintervals oi time displaced 180 electrical degrees. valspi' time to energize an associated load cir- In the particular embodiment of the invention cuit. I provide an excitation means or circuit illustrated, I have chosen to show the inductive which generates an alternating voltage of peaked network as comprising a transformer 4 having wave form having symmetrical positive and nega plurality of primary windings I and two groups ative peaks. The excitation circuit is connected of electrically displaced secondary windings 6, I, to the immersion-ignitor control members 8 and 9, l0, H. The two groups of secondary through suitable current dividing reactors in orphase windings may be connected in the convender to assure the simultaneous transmission of tional double Y relationship by the employimpulses of current to the control members of, ment of an interphase transformer I2 having an electric valves whichare connected to operate intermediate point connected to the negative conductor 3 of the direct current load circuit. The translating system also includes a plurality of pairs of electric valve means, each pair of which is connected to a different one of the phase windings 6-H, inclusive. The pairs of electric valves are intended to conduct current in parallel relationship. For the purpose of illustrating my invention, only electric valve means 83, M

and the pairs 'of electric valve means it, it and 95, it in order that the respective pairs conduct current in parallel relationship.

Although in the various embodimentscf my invention described, I have shown the pairs of electric valve means as being interconnected through a current dividing means, such as auto-transformers ll and i8, 1' have found that by using the control or excitation circuits described hereinafter that pairs of electric valve means may be operated in parallel relationship without employing auxiliary current dividing auto-transformers or reactors. Therefore, it is not neces sary to employ the current dividing means unless these elements are required.

The electric valve means iii-i6, inclusive, are preferably of the type each comprising an anode :9. a cathode such as a, mercury pool cathode 20,

and an immersicn-ignitor control member 2!. The immersion-ignitor control members iii are preferably of a material such as boron carbide or silicon carbide and which serve to establish an arc discharge between the anode and the cathode upon the transmission of a predetermined minimum critical value of current between the control member andthe cathode. If desired, the

electric valves l3-lfi each may be provided with an auxiliary or relieving anode 22 which is connected tothe associated control member 25 on relieving anodes 22 a substantial voltage and upon the establishment of an arc discharge or the establishment of a cathode spot on cathodes 28, this voltage will cause most of the excitation current to he transferred to the relieving anodes and me, and which is assigned to the assignee of aseaceo alternating current supply circuit 4 through a transformer 36 and a phase shifting device 3i. If desired, the excitation means may also comprise a capacitance 32 which is connected acrossthe secondary winding of, transformer 38 and which serves to increase the impulse ofvoltage produced across the terminals of inductance 26.

While I have illustrated the impedance element or inductance 26 as being a specific type, such as an autotransformer, I may employ within the scope of my invention other impedance elements such as various combinations of resistances, capacitances, or inductances in place of the inductance 26. Furthermore, the impedance element may comprise an asymmetrical conducting device, such as a rectifier of the contact type or a plurality of rectifiers of the contact type poled in a manner to permit the desired alternate energization Of electric valves which are intended to operate 180 out of phase. An arrangement of this type is described and claimed in the copending patent application Serial No. 374,716, filed January 16, 1941, by E. F. W. Alexanderson the present application.

It will be noted that the excitation system illustrated supplies excitation current to control members 28 of the pairs of electric valves connected. to windings 8 and 9 which are connected to phase windings displaced 189 electrical degrees with respect to the voltage of the alternati'ng current circuit 4. Furthermore, the electric valves of each pair are intended to conduct current simultaneously, and consequently the impulses of current transmitted to the control memberg 2i of each pair must be transmitted thereto substantially simultaneously and must be displaced 180 electrical degrees with respect to the impulses transmitted to the control members of the pair of electric valves associated with the dies metric winding.

In order to accomplish the above stated desired 22, thereby relieving the duty imposed on the control member. l

I provide an excitation system for energizing the control members M of the electric valvemeans. Only the excitation system for the electric valves 53, M and l5, i8 is illustrated. It is, of course, to be understood that similar excitation directional conducting devices 3? and SB assuresactors 33 and 343 which are connected to the control members and relieving anodes 22 of the pairs of electric valve means 52, it and i5, i6, respectively. The current dividing reactors 33 and 36 are provided with intermediate connections and 35, respectively, and are connected to terminal connections El and 28 of the inductance 26 through suitable unidirectional conducting devices SI and 38. The employment of unithe transmission of only unidirectional current to means'are intended for the pairs of electric valves (not shown) associated with the electrically displaced phase windings 6, it and l, M. The excitation system comprises an excitation means 26 which produces a periodic or alternating voltage of peaked wave form having symmetrical positive and negative peaks. This excitation means 2% comprises a saturable inductive reactance or deimmersion-ignitor control members 2 i, and by virtue of the employment of current dividing reactors and 35 only one unidirectional conducting device is required for each pair of electric valves.

The operation of the embodiment of my invention shown in Fig. 1 will be explained by considering the system when it is operating as a polyphase rectifier to transmit direct current to the vice 25, which may be selfsaturable, and which includes an impedance element, such, as an inductance 26, having terminal connections 27! and 28 and an electrically intermediate connection 29.

be positioned to be an exact center tap, if desired. The excitation means 2 5 is energized from any suitable source of alternating current of the desired frequency and may be energized from the The electrically intermediate connection 29 may load 'circuit from the alternating current supply circuit. The various pairs of electric valve means conduct current in a predetermined order determined by the phase relationship of the voltage of secondary windings 5-H. Due to the phase voltage equalization of the interphase transformer 62, pairs of electric valves associated with the phase windings in the two groups of windings conduct current during common intervals of time; that is, each pair of electric valves conducts current during electrical degrees but conducts current for only 60 electrical degrees with any one other pair of electric valves associated with the other group. In addition, the electric valve means of each pair conduct current simultaneously and in parallel relationship. The excitation system controls the pairs of electric valves to conduct current in a predetermined order or sequence, and also energizes the control members 2| so that the electric valves of each pair conduct current during the same interval of time and, hence, conduct the same average value 01' current.

Considering the operation of the excitation system in more detail, the excitation means 24' including the saturable device 25, acting in conjunction with the inductance 26, produces an alternating voltage of peaked wave form and the positive and negative impulses or peaks are symmetrical.

electric valves, such as electric valve I5, is rendered conducting prior to the electric valve IS, the flow of current through the right-hand portion of current dividing reactor 34 will effect an increase of voltage impressed on control member 2| electric valve means It. I have found, as a practical matter, that the voltage impressed onthe control member 2| of the electric valve means I6 is substantially doubled if the electric valve means It does not begin to conduct current in substantial simultaneity with the electric valve means I5.

Upon initiation of arc discharges within the electric valve means l and It, the current transmitted through the resistance 23 eflects an increase of the voltage impressed on relieving anodes 2|, thereby transferring the greater portion of the excitation current to the relieving anodes and reducing the load imposed on the control members. Y

During the next half cycle, that is 180 electrical degrees later, the terminal 21 of inductance 26 will be positive in potential relative to connection 28-andpositive impulses of current will be transmitted to control members 2| of electric valve means |3 and I4, thereby rendering these electric valves conducting simultaneously.

Phase shifting device. 3| may be adjusted or controlled to control the voltage impressed across the direct current load circuit. Adjustment of the phase shifter 3| controls the time during the respective positive half cycles of anode-cathode voltage at which theimpulses of current are transmitted'to control members 2| and, hence, controls the magnitude of the load voltage;

Fig. 2 represents a portion of the circuit shown in Fig. 1 and corresponding elements have been assigned. likereference numerals. In the ar- During one interval of time, for example in that interval of time during which it is tue of this connection, the'relieving anodes 22 relieve the duty imposed on the unidirectional conducting devices 39-42 by transferring the excitation current from the control members 2| upon initiation of arc discharges. The system shown in Fig. 2 operates substantially the same as that explained above in connection with th arrangement of Fig. 1.

Fig. 2a diagrammatically illustrates afurther.

embodiment of the arrangement shown in Fig. 2 and only a. portion of the excitation system is shown. In the arrangement of Fig. 2a, the intermediate connections 35 and 36 of the current dividing reactors 33 and 34 are connected directly to the terminal connections 2! and 28 of inductance 26. Transfer resistances 23a and 231) are connected in series relation with the rectiflers- 1 4| and 42 and serve to effect the transfer of most of the excitation current from the control members 2| to the relieving anodes 22 as soon as an arc discharge is established in the electric valve means I5 and I6. In thearrangement of Fig. 2a, it will be noted that the unidirectional conducting devices 31 and 38 are not employed.

The system shown in Fig. 21: operates to transmit unidirectional impulses of current of peaked wave form to the control members 2| of the pairs of electric valve means simultaneously. The unidirectional conducting devices 4| and 42 assure the transmission of only unidirectional current to control members 2|, and the relieving anodes 22 are connected in a manner to transfer the excitation current from the control members 2| upon initiation of arc discharges within theelectric valves.

-The arrangement of Fig. 3 represents a portion of the circuit shown in Fig. 1 and corresponding elements have been assigned like reference numerals. In the arrangement of Hg. 3,

I have provided an excitation system wherein I simplicity of circuit construction is provided and wherein only a minimum number of unidirectional conducting devices are required inorder to obtain satisfactory operation of the translating system. It will be appreciated thatby reducing the number of unidirectional conducting devices, I provide an arrangement which not only reduces the cost of the excitation system but also reduces the probability of failure of the system due to the failure of operation of the unidirectional conducting devices. More specifically, in the arrangement of Fig. 3 the unidirectional conducting devices 48- and 44 are connected between terminals 28 and 21 of the inductance 26 and the intermediate connections of current dividing reactors 33 and 34. In addition,

- I provide a second pair of current dividing rerangementof Fig. 2, in addition to employing the unidirectional conducting devices 31 and 38, I connect unidirectional conducting devices 39-42 in series relation with control members 2| of electric valve means li-ll, respectively. By virvices 42 and 44. That is, unidirectional conducting devices 43 and 44 are required to conduct current only until the arc discharges are established within the electric valve means. As soon as are discharges are established, the excitation current is transferred immediately. to the relieving anodes 22 and most of the excitation current then flows through current dividing reactances 48 and 46, effectively bynot only the control members it but also by=passing the unidirectional conducting devices 58 and M.

- In explaining the operation of the arrange-' ment shown in Fig. 3 let it be assumed that the terminal 28 of inductance 2a is positive in potential relative to terminal 21 at the time imme diately preceding the transmission of positive impulses of current to control members 28 of electric valve means 88 and it. Initially, the current is transmitted through the unidirectional conducting device 63, the two portions of the current dividing reactor 33 to the control members 20 of electric valve means is and 6%. "Upon the establishment of cathode spots and arc discharges within the electric valve means 33 and i l, current is transferred to the relieving anodes 22, This operation causes current to flow through the two portions of current dividing reactor 65 and efiectiveiy by-passing unidirectional conducting device 33, current dividing reactor 33, resistances 23 and control members 25. In like manner, the portion of the circuit associated with electric valve means l and it operates to relieve the duty imposed on unidirectional conducting device 66, current dividing reactor 3t, resistances 28 and control members it of electric valve means it and id as soon as are discharges are initiated.

While I have shown and described my invention as applied to particular systems of connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope oi my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, an alternating current circuit, a direct current load circuit, electric translating apparatus connected between said circuits and comprising a pair of electrically displaced phase windings and two pairs of electric valve means each associated with a difierent one of said phase windings, current dividing means connected between each pair of electric valve means and the associated phase winding, said electric valve means each being provided with a control member for controlling the conductivity thereof, an excitation means for energizing the control members for causing the electric valve means in each pair to conduct current in parallel and for causing the pairs of electric valve means to conduct current during intervals of time displaced 180 electrical degrees and including means for producing a periodic voltage having symmetrical peaks displaced 180 electrical degrees and comprising a saturable inductive reactance comprising a winding connected in series relation with an impedance element provided with terminal connections and a connection electrically intermediate the terminal connections, said intermediate connection being con-- nected to one terminal of said direct current circuit, and individual means connected between" asaaeeo each pair to conduct current in parallel and for causing the pairs of electric valve means to conduct current during intervals of time displaced electrical degrees and comprising means for producing a periodic voltage having symmetrical peaks displaced 180 electrical degrees and including a saturable inductive reactance comprising a winding connected in series relation with an impedance element provided with terminal connections and a connection electrically intermediate the terminal connections, said intermediate connection being connected to one terminal of said direct current circuit, and means connected between each terminal and the control members of a diiierent pair of said valves for supplying to the control members in the respective pairs impulses of current of peaked wave form to render the electric valves in the respective pairs conducting simultaneously and each including a unidirectional conducting device and a current dividing reactor.

3. In combination, an alternating current circuit, a direct current-load circuit, electric translating apparatus connected between said circuits and comprising a pair of electrically displaced phase windings and two pairs of electric valve means each associated with a diiierent one of said phase windings, current dividing means connected between each pair of electric valve means and the associated phase winding, said electric valve means each being provided with a control member for controlling the conductivity thereof, an excitation means for energizing the control members for causing the electric valve means in each pair to conduct current in parallel and for causing the pairs of electric valve means to conduct current during intervals of time displaced 180 electrical degrees and comprising means-for producing a periodic voltage having symmetrical peaks displaced 180 electrical degrees and comprising a saturable inductive reactance comprising a winding connected in series relation with an impedance element provided with terminal connections and a connection electrically intermediate the terminal connections, said intermediate connection being connected to one terminal of said direct current circuit, means for transmitting to the control members of the electric valves in each pair impulses of current of peaked wave form to render the electric valves in each pair conducting simultaneously and during corresponding intervals of time and comprising a pair of current dividing reactors each having an intermediate connection and a pair of unidirectional conducting devices, means connecting one of said devices between one of said terminal connections and the intermediate connection of; one of the current dividing reactors, and means connecting the other of said devices between the other of.

. said terminal connections and the intermediate connection of the other of said current-driving reactors.

cuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising a pair of electric valve means, said electric valve means each comprising an anode, a cathode, an immersion-ignitor type control member and a relieving anode, excitation means for producing a periodicvoltage of peaked wave form and comprising a saturable inductive reactance, a current dividing reactance connected to thecontrol members, a unidirectional conducting device connected between said excitation means and said current dividing reactor, and a second current dividing reactor connected between said excitation means and the relieving anodes.

5. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits and comprising a pair of electric valve means, said electric valve means each comprising an anode, a cathode, an immersion-ignitor type control member and a relieving anode, excitation means for producing a periodic voltage of peaked wave form and comprising a saturable inductive reactance, a current dividing reactance connected to the control members, a unidirectional 'conductingdevice connected between said excitation means and said current dividing reactor, and a second current dividing reactor connected between said excitation means and the relieving anodes and arranged to relieve the duty imposed on said control members and said unidirectional conducting device upon initiation of arc discharges in said electric valve means.

ALBERT H. MI'I'IAG. 

